He general meant of challenging himself or other to take part into 100 days of magick. Basically he want to see how much he can learn if he continuously study for those days and No! That is a bad idea as it will put so much strength on your brain and it is always better to take a small step then a big one but dangerous so please don't be impulsive if that what you meant. it will help you brain to remember them and also try to practice them as well as learning about it.

I know, that why i said s/he need to take a small step and stop being impulsive. Magick is not something that it will just pop up, it need practical works as well as knowing every corner of it effect and reason behind it.

Brysing if a book can be read in 3 months then surely magick can be learned in 3 months! Common knowledge obviously.

Well it sounds fun in theory, but you might wish to come to a common goal. The YouTube Pagan Challenge for example is a series of videos answering a series of questions like when did you get started, what does magick mean to you, what does this season represent to you, who do you admire, stuff like that. Not really a spell a day, but still relevant. This path isn't just about spell casting, so perhaps research various things to study, questions to contemplate, and things to practice [like meditate for 30 minutes or observe the season] I don't know of any 'challenge' but I have come across a series of questions and activities over the years to help me at various points in my life when I was stagnant. Try getting a copy of Deborah Blake's 'The Goddess is in the Details' it helps further your study and gives questions/activities to help you on your next step.